As kl522 relates, there are lots of reports about udevd problems. Maybe hardware related, too. I wrote about the conflicting memtest results above. But hardware problems should show up elsewhere too, I think. And here, it seems that everything is working fine, except for udevd. I start wondering if there is some kind of slight incompatibility between Knoppix and udevd in the kernel version 2.6.1 uses.